|5||Automatic Three Piece Bike Lock
|Automatic Bike Lock
Problem: Properly securing a bike can take a lot of time and can be done improperly, leaving your bike susceptible to theft. The main way to properly secure a bike involves using a u-lock for the back wheel along with a chain that will lock the bike to a rack and secure the front wheel. This act takes time and some cyclists do not utilize two locks, making it easy for their bike to be taken. Our product seeks to alleviate this. We will create a three piece bike lock that is able to lock the front and back wheels along with locking the bike to a rack. This system will only require for the user’s fingerprint and will lock the bike in a fast and easy process. The main goal behind this project is to make bike locking a seamless and secure process.
Solution Overview: Our solution consists on having three separate locking mechanisms that are responsible for the following: locking the rear wheel, the front wheel, and locking the bike to a bike rack. A fingerprint sensor along with a microcontroller will be used to lock/unlock the three locks. To prevent theft, an alarm system will also be implemented and will audibly signal whenever a lock is being compromised. There will be 2 different locking mechanisms implemented for the device. The middle one will be different so that the user can secure their bike to different types of bike racks. Each of the five subsystems will let a user simply place their bike next to a rack and use their fingerprint to seamlessly lock their bike. This locked bike will be incredibly difficult to steal and saves the user time in securing their bike.
Subsystem #1 Microcontroller : This subsystem takes input from the fingerprint sensor and uses this information to control the locking and alarm systems of the project. Another way that the microcontroller controls the alarm system is via feedback that it obtains from the locking system; if the feedback, in the form of current, indicates that a lock is being compromised then the alarm system will go off due to the microcontroller. We currently plan on using a raspberry pi as the microcontroller but this may be replaced with a stm 32.
Subsystem #2 Fingerprint Sensor: The fingerprint sensor will take user’s thumb fingerprint allowing the locking circuit to unlock the bike lock. This only occurs when successful authentication happens for the owner of the bike lock, otherwise the bike lock will stay locked. After three failed fingerprint authentication attempts then the alarm system will be activated. The sensor will be mounted on the middle lock.
Subsystem #3 Rear/Front Wheel Lock: This subsystem will utilize a metal wire that will be encased by a curved piece of 3D printed plastic. The metal wire will have two loops at its end and one loop is connected to the teeth of a DC motor, via epoxy. When the user inputs their fingerprint the motor will rotate and move the wire to the other side of the wheel and then a proximity sensor will detect when the plastic is fully inserted to the other side of the housing. We will make a proto actuator that uses a screw, a DC motor, and two gears that will move the screw to secure the wire when the proximity sensor signals that the lock is in the optimal position. This actuator will disengage to allow the user to unlock their bike. To prevent the lock from closing on a spoke there will also be an IR sensor in the plastic piece so that if it detects a spoke the system will stop. On the other side of the wheel there will be white tape so that the sensor will not stop the lock from moving when it is in the lock position.
Subsystem #4 Middle Lock: This subsystem takes in input from the microcontroller.The implementation of the lock is different from the front/rear locks so that the user is free to lock their bike to a variety of different sized bike racks. This system will consist of a chain that will be moved by the user around the bike rack and upon using their fingerprint sensor a linear actuator will be used like a deadbolt to hold the chain in place. A proximity sensor with a LED light will be used to let the user know if they inserted the chain far enough into the lock. A wire will be looped around the chain so that if the chain is cut then the alarm system will be activated. This system will also have a hold button that will allow for only the middle lock to be activated so that the chain can be held when the bike is not locked.
Subsystem #5 Alarm System: This system is responsible for alerting whenever the locks are being tampered with. This alert comes in the form of three speakers that are in each lock. There will be two ways for the system to activate: an unauthorized user attempts to use the fingerprint sensor and one of the locks are cut or damaged. If the alarm system sounds only the users fingerprint will stop the alarm system. The microcontroller will directly control this system by taking in feedback, in the form of current, from the locking circuits.
Criterion for Success:
The high level goals of what our project needs to meet to be effective are:
The Automatic Bike Lock can accurately identify the authorized user’s fingerprint and quickly lock or unlock the bike.
An unauthorized fingerprint will prevent the bike from locking or unlocking. After three successive unauthorized user attempts to use the fingerprint sensor, the bike alarm will sound. If a lock is tampered with or cut, an alarm will sound.
Each lock is able to move it’s wire or rod and secure it in the desired placement with the appropriate signal from the microcontroller.
The bike lock is manufacturable from at most $200 worth of parts.